BIOLOGY Volume 1 - A Guide to General Biology - 2004

2. THE DIVERSITY OF LIFE ON EARTH

2.1. Classification

2.1.1. Why is it needed?

If you have ever watched a child sort coloured sweets, stamps, football tickets, or other items in a collection, you have likely witnessed one of our most characteristic instinctive drives—the desire to put everything in its proper place. This is The Essence of Classification. Classification is the arrangement of items into groups based on shared properties. The branch of science dedicated to the principles, Methods, and rules of classification is called Taxonomy. Why are we so driven to classify everything? According to some biologists, the answer is very simple: we classify objects, phenomena, and events because it gives us a survival advantage. When our perception is overwhelmed by a vast number of different stimuli, we begin to classify them in an effort to make sense of them. Our initial steps in classification may be flawed; for instance, a toddler might occasionally call any four-legged object a dog. However, humans gradually develop a reliable system that helps them cope with The complexity of the surrounding world.

Up to one and a half million different species of living organisms have been discovered on Earth, yet estimates suggest this number could actually be between 10 and 100 million. It is hardly surprising, therefore, that attempts to classify these organisms date back to ancient times. Existing classifications vary depending on their intended purpose. In ancient China, for example, the animal kingdom was divided into groups that, to put it mildly, seem rather bizarre today. These included mythical creatures, stray dogs, animals that had once broken a flower vase, and those resembling flies from a distance. A more familiar example of early classification is the division of plants into poisonous and edible, or animals into flying and non-flying. In modern classifications, as we will see later, a strong emphasis is often placed on the evolutionary relationships between organisms.

As our knowledge of living organisms expands, classification evolves accordingly. However, it should be kept in mind that no existing system of classification can be considered perfect, as all of them are designed for our own convenience.